Effect of particle size of rice bran on gamma-oryzanol content and compounds Kelly Cristina Massarolo * , Anelise Christ Ribeiro, Eliana Badiale Furlong, Leonor Almeida de Souza Soares Laboratory for Mycotoxins and Food Science, Post Graduate Program in Engineering and Food Science, School of Chemistry and Food, Federal University of Rio Grande - FURG, Avenida It alia km 8, Campus Carreiros, 96203-900 Rio Grande, RS, Brazil article info Article history: Received 21 August 2016 Received in revised form 22 January 2017 Accepted 7 March 2017 Available online 21 March 2017 Keywords: Antioxidant Extraction yield Inhibition Phytochemical abstract The reduction of particle size can facilitate the extraction of phytochemical compounds. In this study was evaluated the effect of rice bran particles size in the yield and characteristics of g-oryzanol compound. The g-oryzanol extraction was realized with hexane and isopropanol solvents and quantification by spectrophotometric method. The g-oryzanol extracts were characterized in relation of theirs majority components in HPLC-UV and the antioxidant capacity verified by the free radical DPPH C consumption. The g-oryzanol yield varied of 0.10e1.54 mg/g of bran, and the highest yield was obtained in particles smaller than 0.39 mm. The g-oryzanol majority components presence (cycloartenyl ferulate, 2,4- methylenecycloartanyl ferulate, campesteryl ferulate e b-sitosteryl ferulate) in the extracts was confirmed and verified differences in the profile of this components in function of different particles sizes. The g-oryzanol extract obtained from particle sizes between 0.73 and 1.67 mm demonstrated most specific inhibition of DPPH radical (6.7%) and IC 50 6.63 mg/mL. When the particle size is reduced, the access surface to the extraction solvent is increased resulting in more g-oryzanol extraction, however the extract from larger particles was more efficient as antioxidant. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction The large amount of co-products, generated in agricultural in- dustry, arouse interest in exploiting them to obtain phytochemicals and antioxidants, it is extremely important to use the agro- industrial co-products in efficient form, adding value to them and reducing the environmental impact. The interest in natural foods has required research to identify natural antioxidants focusing on its extraction. In the productive chain of rice (Oryza sativa), one of the most produced and consumed grain, there is a high amount of by- products. Each 100 kg of rice in husk generate about 5e10 kg of bran, which has conventional utilization to animal feed and oil extraction (Burlando and Cornara, 2014). However, rice bran is a rich source of oil that due to its unsa- ponifiable fraction with antioxidant as g-oryzanol, gives to rice oil more resistance in oxidation and in deterioration g-oryzanol. The g-oryzanol, an example of natural compound and antioxidant, it can be extracted from rice bran, it is a mixture of ferulic acid esters and exercises functions in cholesterol reduction (Cicero and Gaddi, 2001), being anticancer (Yasukawa et al., 1998), anti-inflammatory (Islam et al., 2008), antidiabetic (Son et al., 2011) and antioxidant (Winkler-Moser et al., 2012). This mixture of compounds has shown to be promising in the development of functional foods and industrial application to stabilize oils and fats (Lerma-Garcia et al., 2009). The g-oryzanol antioxidant potential is due to ability hydrogen donation of ferulic acid phenolic group (Nystrom et al., 2005). Ferulic acid esterified plant sterols, such as the g-oryzanol, in- creases the antioxidant potential promoting molecular access to hydrophobic components that are more susceptible to oxidative cellular destruction, because the antioxidant potential increases with the extent of hydroxylation of aromatic rings (Graf, 1992). The efficiency of solid/liquid extraction processes is affected by critical processing parameters, such as temperature, solvent nature, the solid matrix structure (especially size particle) and extraction time (Franco et al., 2007). Antioxidants are responsible for inhibition and free radicals * Corresponding author. E-mail address: kelly_massa@hotmail.com (K.C. Massarolo). Contents lists available at ScienceDirect Journal of Cereal Science journal homepage: www.elsevier.com/locate/jcs http://dx.doi.org/10.1016/j.jcs.2017.03.012 0733-5210/© 2017 Elsevier Ltd. All rights reserved. Journal of Cereal Science 75 (2017) 54e60